Network element system method computer program and data carrier for network optimisation

ABSTRACT

A system is provided for optimisation processing in a cellular communications network having a central element ( 30 ) and a number of distributed network elements ( 40, 42, 44, 46, 48, 50 ). Each network element ( 40 - 50 ) is coupled to the central element, and each is arranged to obtain optimisation data and has a pre-processing arrangement ( 120 ) for pre-processing the optimisation data. The central element ( 30 ) then receives and processes this pre-processed optimisation data to produce optimisation code for optimising the performance of the network. In this way less data needs to be backhauled to the central element ( 30 ), and less processing is required at the central element ( 30 ), thereby improving the scalability of the network.

FIELD OF THE INVENTION

This invention relates to cellular Radio-Frequency (RF) networks andparticularly but not exclusively to network optimisation processing insuch networks.

BACKGROUND OF THE INVENTION

In the field of this invention cellular networks include a number ofnetwork elements (such as base stations) which operate using callprocessing software. Such software is updated periodically by themanufacturer of the network element. Typically these software updatesare downloaded from an Operations and Maintenance Center (OMC) when anew software release is available for the Network Element.

It is also desirable to be able to optimise the performance of thenetwork as a whole. Such optimisation is typically performed by anoptimisation manager.

Referring now to FIG. 1, there is shown a prior art cellular networksuch as a GSM (Global System for Mobile communication) network. Anoptimisation manager 5 which may be part of or co-located with the OMCof the network is coupled via first and second Base Station Controllers(BSCs) 7 and 9 respectively to a number of Base Stations 10, 12, 14, 16,18, 20. Each of the Base stations 10-20 and the BSCs 7 and 9 are networkelements of the network.

Each base station 10-20 typically provides a ‘cell’ of the network, andcontains a number of operating parameters for the cell such as powersettings, frequency settings and the like. These parameters may beadjusted in order to optimise power consumption, signal quality andother characteristics of the cell.

Typical optimisation architecture is based on the collection of asignificant amount of data from the cells, which is then processedcentrally to provide reports for each cell and combined recommendationsfor topological planning. This is done by the optimisation manager 5‘backhauling’ measurement data from each base station, and thenprocessing this backhauled data using performance optimisationalgorithms in order to provide the reports and recommendations.

Considering the first base station 10 and its associated cell,measurements from the cell are backhauled to the optimisation manager 5periodically, where they are processed to derive optimised parametersettings for the base station 10, as well as the combinedrecommendations.

A problem with this arrangement is that a large amount of optimisationdata must be sent from each network element to the optimisation manager5 (illustrated by the thick lines of FIG. 1).

Furthermore all of the optimisation data must be processed at theoptimisation manager 5 (illustrated by the dial 6). This restricts theexpansion of the network, as each additional cell leads to a furtherincrease in the amount of optimisation data to be transferred andprocessed, and requires that the processor at the OMC/optimisationmanager 5 be highly specified in order to achieve optimisation resultsand hence optimise the performance of the network in a reasonable timeperiod.

A need therefore exists for a network element, system, method, computerprogram and data carrier wherein the abovementioned disadvantages may bealleviated.

STATEMENT OF INVENTION

In accordance with a first aspect of the present invention there isprovided a network element as claimed in claim 1.

In accordance with a second aspect of the present invention there isprovided a system as claimed in claim 2.

In accordance with a third aspect of the present invention there isprovided a method as claimed in claim 8.

In accordance with a fourth aspect of the present invention there isprovided a method as claimed in claim 11.

In accordance with a fifth aspect of the present invention there isprovided a computer program as claimed in claim 12.

In accordance with a sixth aspect of the present invention there isprovided a data carrier as claimed in claim 13.

Preferably each arrangement for providing element optimisationpre-processing includes an arrangement for downloading software toenable element optimisation pre-processing. Each network elementpreferably has a processor partition arrangement such that separateprocesses operate for call processing and optimisation processing.Preferably the processor partition arrangement comprises a contentionscheme which gives priority to call processing. Alternatively, theprocessor partition arrangement preferably comprises more than oneprocessor.

Preferably the element optimisation processing includes an arrangementfor providing processed element optimisation data directly to thenetwork element, so that localised optimisation is provided at eachnetwork element.

The optimisation processing preferably comprises a number ofinterrelated part-processes and the pre-processing of elementoptimisation data comprises those part-processes of the optimisationprocessing which only require the optimisation data available at eachnetwork element. Preferably the element operating parameters containmeasurement and messaging information relating to the element.

In this way cellular network optimisation processing is performed in adistributed manner at each of the network elements, thereby reducingdata backhaul requirements, central processing requirements, andproviding much greater scalability. Furthermore, localised optimisationof each network element is also facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

One network element, system, method, computer program and data carrierfor network optimization incorporating the present invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings, in which:

FIG. 1 shows a block-schematic diagram of a prior art communicationssystem

FIG. 2 shows a block-schematic diagram of a cellular communicationssystem in which the invention may be used;

FIG. 3 shows a network element forming part of the cellularcommunications system of FIG. 2; and

FIG. 4 shows an illustrative flow diagram of an optimisation processusing the system of FIG. 2 and the network element of FIG. 3.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 2, there is a block-schematic diagram of a GSMcellular communications system. An optimisation manager 30 is coupledvia BSCs 32 and 34 to a number of base stations 40, 42, 44, 46, 48, 50,which typically control a cell of the network. Each of the base stations40-50 and the optimisation manager 30 has a diagrammatic representationof a dial indicating the amount of optimisation processing which takesplace thereat. This will be further explained below.

Briefly stated, in operation each of the base stations 40-50 operates asa flexible optimisation processing platform, in a manner to be furtherdescribed below. In this way the processing of measurement data ispartially distributed to each network element, as illustrated by thedials of base stations 40-50.

Referring now also to FIG. 3, there is shown a network element 55 of acellular network, such as the base station 40 of the network of FIG. 2.The network element 55 has an operations and maintenance agent 60 whichis arranged to control data transfer to the optimisation manager 30, acall processing agent 70 which executes call processing, a configurationmanagement database 80 which contains operating parameters for thenetwork element 55, and an optimisation processing platform 100.

The optimisation processing platform 100 has a data compression engine110, an RF measurement report pre-processing engine 120, and downloadedoptimisation software 130. The operation of each of these elements willbe further described below.

The flow diagram of FIG. 4 shows the process which takes place at anindividual network element when performing local optimisation on theleft side (boxes 210, 220, 230, 240, 250 and 260) and network-wideoptimisation on the right side (boxes 215, 220, 230, 245, 255 and 265).

In operation, and referring now also to FIG. 4, network-wideoptimisation is initiated by the optimisation manager 30 (box 215). Theoptimisation processing for any one network element, such as networkelement 40, can be notionally sub-divided into those part-processeswhich require optimisation data not available in network element 40(such as information from neighbouring network element 42) and thosepart-processes which only require the element optimisation data which isavailable in the network element 40. Since the majority of theoptimisation processing is found in the latter category (i.e. cellspecific and not dependent upon data from surrounding network elements)it is therefore possible to distribute this cell specific processing tothe network element 40.

Each network element collects element optimisation data from within itsown cell (box 220). This data contains element operating parametersincluding measurement and messaging information, which may be extractedfrom ‘call trace’ information taken from each call made by a mobile unitoperating in the cell of the network element. The data includes signalstrength values, quality measurements, timing information and the like.

In the network element 55, call trace information is extracted from thecall processing agent 70 by the pre-processing agent 120 (arrow 75),where element optimisation pre-processing (box 230) takes place (thatis, those portions of optimisation processing which can be done withoutrequiring information from other network elements).

This pre-processed element optimisation data is then compressed by thedata compression agent 110, before being sent to the operations andmaintenance agent 60 (arrow 65) for backhaul by the optimisation manager30 (box 245). This significantly reduces the data backhaul load since a)it is compressed, and b) the processed data which is backhauled is farless than unprocessed data would be. The central processing of theoptimisation manager 30 has only to deal with the combination andintegration of the results of the distributed processing (as shown bythe dial 31, in comparison to the dial 6 of FIG. 1. This thereforeprovides reduced backhaul requirements, reduced central processingrequirements, and therefore much greater scalability.

The optimisation manager 30 then completes the optimisation processingand provides the results to the configuration management (CM) databasesof each of the network elements (box 255). For the network element 55,the results (which are specific for each cell) may be downloaded via theoperations and maintenance agent 60 and the call processing software 70to the CM database 80 during a software release update of the callprocessing software 70. The network is then optimised (box 265).

However, it is also possible to download the results to the optimisationprocessing platform as the downloaded optimisation software 130. Thiscan be used to update the CM database 80 (via the arrow 85)independently of the call processing software 70, thereby facilitatingoptimisation processing independently of call processing softwarerelease updates.

In this way the structure inherently also supports automatic localoptimisation (commencing at box 210), whereby measurement data takenfrom the cell of the network element 55 (box 220) may be processed bythe pre-processing agent 120 (box 230), and used by the downloadedoptimisation software 130 to update the cell parameters in the CellManagement (CM) database 80 (arrow 85, box 240), independently of therest of the network.

When the network element cell begins to function using the updatedparameters from the CM database 80 (box 250), local optimisation iscomplete (box 260).

This ‘localised’ level of optimisation does not take account ofmeasurement data or behaviour of neighbouring cells, and is thereforenot as comprehensive as ‘global’ (i.e. network-wide) optimisation.However, it does provide partial optimisation, and significantly, anetwork element may be programmed to perform a ‘localised’ optimisationas often as is desired without any backhaul or central processingoverhead.

Local optimisation may occur in conjunction with or independently ofnetwork-wide optimisation. In other words, the left-and right-hand partsof FIG. 4 may operate independently or together, as the diagramsuggests. Obviously any local optimisation may be quickly superseded bynetwork-wide optimisation, as the parameters provided by network-wideoptimisation are the result of factoring in data from other cells.

The flexible processing platform 100 has a well-defined interface withthe call processing software 70. It is important to ensure that callprocessing is protected by this interface such that any faults in thedownloaded optimisation software 130 do not adversely affect the callprocessing activities of the network element 55. This is becauseoptimisation software is subject to iterative improvement and is nottypically tested as comprehensively as call processing software,therefore it is more liable to contain errors.

The downloaded optimisation software is thus completely independent ofthe call processing software 70. The architecture of the network element55 is effectively partitioned, and may be defined in such a way that thecall processing software 70 always has priority when processors areshared, or alternatively that separate processors are used for callprocessing and for optimisation. The call processing software 70 neednot even be aware of any changes to the optimisation functionality ofthe network element 55.

It will be understood that the network element and system describedabove provides the following advantages:

-   -   Reduced backhaul of measurement data to the optimisation manager        30;    -   Improved scalability of the network;    -   Reduced central processing requirement at the optimisation        manager 30;    -   Increased frequency of network optimisation; and    -   Inherent support for Automatic Optimisation at the Network        Element 55.

It will be appreciated that alternate embodiments to the one describedabove are possible. For example, it will be understood that the aboveexample of a GSM network is illustrative only, and the arrangement isapplicable to any cellular network, including third generation cellularnetworks such as UMTS (Universal Mobile Telephone Standard) and CDMA(Code-Divided Multiple-Access) 2000.

Furthermore, the above example shows distributed and localisedprocessing occurring only at the base station network elements 40-50.However the network may be arranged such that, for example, the possestation controller elements 32 and 34 may provides some furtherlocalised pre-processing of the pre-processed network element data froma number of the base station network elements 40-50. In other wordspre-processing may be arranged to occur at each ‘tier’ of the network,where pre-processed data from the ‘tier’ belong is further processed tothe extent possible and appropriate for that tier.

In the case of UMTS networks, it will be appreciated that distributed,localised processing may occur at the Node B level (equivalent to basestation network elements 40-50) and also at RNC (Real NetworkController) level (equivalent to base station controller elements 32 and34).

1. A network element for use with a cellular communications networkhaving a plurality of network elements and a central element, thecentral element being arranged to receive, combine and process elementoptimisation data from at least two of the plurality of networkelements, the element optimisation data of each element containingelement operating parameters, the network element comprising: means forobtaining element optimisation data from within the network element; andmeans for providing pre-processing of the element optimisation data;wherein the element optimisation data is pre-processed before it isreceived, combined and processed at the central element; and the networkelement having a processor partition arrangement such that separateprocesses operate for call processing and optimisation processing.
 2. Asystem for providing optimisation processing in a cellularcommunications network, comprising: a central element having means forreceiving, combining and processing element optimisation data to produceoptimisation code for the network; and a plurality of distributednetwork elements coupled to the central element, each having means forobtaining element optimisation data from within that network element andmeans for providing optimisation pre-processing of the elementoptimisation data, the element optimisation data containing elementoperating parameters; wherein each network element is arranged topre-process its element optimisation data before it is received,combined and processed at the central element; and each network elementhas a processor partition arrangement such that separate processesoperate for call processing and optimisation processing.
 3. The networkelement of claim 1 wherein each means for providing element optimisationpre-processing includes means for downloading software to enable elementoptimisation pre-processing.
 4. The network element of claim 1 whereinthe processor partition arrangement comprises a contention scheme whichgives priority to call processing.
 5. The network element of claim 1wherein the processor partition arrangement comprises a plurality ofprocessors.
 6. The network element of claim 1 wherein the elementoptimisation processing includes means for providing processed elementoptimisation data directly to the network element, wherein localisedoptimisation is provided at each network element.
 7. A method forproviding optimisation processing in a cellular communications networkhaving a plurality of network elements having a processor partitionarrangement such that separate processes operate for call processing andoptimisation processing and a central element, the method comprising thesteps of: obtaining element optimisation data at each network element,the element optimisation data of each element containing elementoperating parameters; pre-processing the element optimisation data ateach network element; receiving and combining the pre-processed elementoptimisation data from each network element at the central element; andprocessing the combined optimisation data at the central element.
 8. Themethod of claim 7 further comprising the step of providing the processedelement optimisation data from each network element directly to thatnetwork element, wherein localised optimisation is provided at eachnetwork element.
 9. The network element of claim 1 wherein theoptimisation processing comprises a plurality of interrelatedpart-processes and the pre-processing of element optimisation datacomprises those part-processes of the optimisation processing which onlyrequire the element optimisation data available at each network element.10. A computer program enabling the carrying out of a method accordingto claim
 7. 11. A record carrier comprising a computer program asclaimed in claim
 10. 12. The system of claim 2 wherein each means forproviding element optimisation pre-processing includes means fordownloading software to enable element optimisation pre-processing. 13.The system of claim 2 wherein the processor partition arrangementcomprises a contention scheme which gives priority to call processing.14. The system of claim 2 wherein the processor partition arrangementcomprises a plurality of processors.
 15. The system of claim 2 whereinthe element optimisation processing includes means for providingprocessed element optimisation data directly to the network element,wherein localised optimisation is provided at each network element. 16.The system of claim 2 wherein the optimisation processing comprises aplurality of interrelated part-processes and the pre-processing ofelement optimisation data comprises those part-processes of theoptimisation processing which only require the element optimisation dataavailable at each network element.
 17. The method of claim 7 wherein theoptimisation processing comprises a plurality of interrelatedpart-processes and the pre-processing of element optimisation datacomprises those part-processes of the optimisation processing which onlyrequire the element optimisation data available at each network element.